"Nobody in life gets exactly what they thought they were going to get, but if you work really hard, and you're kind, amazing things will happen. I'm telling you...amazing things will happen" --Conan O'Brien
It doesn't have to be your favorite song - but what song do you feel relates to your life the most, or just defines you/your personality/etc.? In simple terms, basically anything that could work as the opener for your own show, haha.
Despite having no lyrics, mine would have to be "A New Career in a New Town" by David Bowie. I love that song.